Remote controlled slide changer for overhead projector

ABSTRACT

A remotely-controlled transparency slide changer moves a stack of slides on a spindle in an arc from a position clear of the top of the light box of an overhead projector to a position over the light box, releases the lowermost slide from the stack and returns to its starting position while at the same time a sweep arm moves in the reverse direction to remove a previously exhibited slide from a position over the top of the light box to a position where said slide is clear of the light box and slides down the said spindle into a receiving tray. The upper part of the spindle non-rotatably but slidably receives each of the slides in the stack but the lower part of the spindle is slidably and rotatably received in the exhibited slides.

United States Patent [1 1 Treher Dec. 11, 1973 [76] Inventor: James E.Treher, 609 Oxford Blvd.,

Pittsburgh, Pa. 15234 [22] Filed: Feb. 5, 1973 [211 App]. No.: 329,537

Primary ExaminerLouis R. Prince Assistant Examiner--A. J. MirabitoAtt0rneyWilliam 1-1. Parmelee [57] ABSTRACT A remotely-controlledtransparency slide changer moves a stack of slides on a spindle in anare from a position clear of the top of the light box of an overheadprojector to a position over the light box, releases the lowermost slidefrom the stack and returns to its starting position while at the sametime a sweep arm moves in the reverse direction to remove a previouslyexhibited slide from a position over the top of the light box to aposition where said slide is clear of the light box and slides down thesaid spindle into a receiving tray. The upper part of the spindlenonrotatably but slidably receives each of the slides in the stack butthe lower part of the spindle is slidably and rotatably received in theexhibited slides.

gli1I IS, 11 Drawing Figures REMOTE CONTROLLED SLIDE CHANGER FOROVERHEAD PROJECTOR This invention is for a projector of a type commonlyused for visual education, visual group instruction and like purposes,and more particularly provides for use with such a projector a remotecontrolled transparency or slide changer.

BACKGROUND OF THE INVENTION In an overhead type of projector to whichthis invention relates, there is typically an enclosed light box with alight-transmitting top. The slide or transparency to be projected iscustomarily a letter-size, or larger, sheet that is positioned on top ofthe box, and on which there may be printing, or a drawing, or diagram,or the like. The light which shines up from the box and passes throughthe transparency, which for convenience will hereinafter be termed aslide, although it is quite unlike the conventional small photographicslide commonly used in horizontal projectors. The light, emerging fromthe slide, is collected by a lens or prism arrangement adjustablypositioned above the top of the box and projected horizontally against ascreen, where the indicia or other image on the slide is enlarged andeasily viewed by a group. Such a projector makes possible the enlargedshowing of various types of information, comparative illustrations, andother material without the preparation of conventional miniaturephotographic slides. One objection to such projectors is that, unlikethe more familiar horizontal projector, automatic slide changersremotely operated by a speaker have not to my knowledge been provided. Iam aware that slide or transparency changers for this purpose haveheretofore been disclosed in patents, but I am unaware of any of thembeing commercially available, and I believe this is due to variousreasons of a practical nature.

Without a remotely controlled slide changer the speaker must standbehind the projector with his back to the audience or a considerableportion of it, since the projection range of such instruments does notpermit their location at any great distance from the screen.

This present invention has for its purpose to provide a relativelysimple slide changer for overhead projectors which can be attached tothe projector with little difficulty and which may be remotelycontrolled so that the speaker may be close to the screen or at a podiumwhere he may face his audience or otherwise be to the side of the lineof vision of the audience to the screen.

BRIEF DESCRIPTION According to the present invention a vertical spindleor shaft at one corner of the light box supports a stack of slide unitsor transparencies, one above the other, much in the manner that a stackof record disks are mounted on a spindle of an automatic record changingphonograph spindle, but the spindle in this instance, unlike the spindleof a record changer, passes through holes in a corner of each of theslides. The stack of slides is normally at one side of the light box.When the operator presses a button, the spindle will rotate 90, bringingthe stack of slides squarely over the lightemitting top of the box. Atthis time the lowermost slide in the stack is released in the samemanner that the lowermost record on the stack in a record changingphonograph is released, and upon being so released slides down onto thetop of the light box in position to be projected. The spindle thenautomatically reverses to remove the remaining slides in the stack fromabove the light box, but the slide which has dropped remains on the box.This is accomplished by having the holes in the corner of the slidenon-circular or with keyways and with the section of the spindle abovethe point of release of a matching cross-section, but with the shaft orspindle being of a circular or other section below the point of release,so that the remainder of slides in the stack yet to be viewed alwaysturns with the spindle but the spindle may rotate relative to each slideafter it has been dropped. The slide itself preferably comprises aunique holder for the transparency so that the slides are sufficientlystiff or rigid to avoid binding on the spindles or sagging.

After the first slide has been viewed it must be moved out of the waybefore a second one is released. To accomplish this, there is a secondshort spindle or shaft with a horizontal wiping or sweep arm pivoted toit, and the second shaft is geared to the first shaft to rotate alwaysin a direction opposite the direction of rotation of the first spindle.As the first spindle rotates in a direction to move the stack back overthe light box, the sweep arm will move in the reverse direction to sweepthe first slide off the top of the light box where this slide so brushedaway is then free to slide down the first shaft into a tray. As eachslide in turn is released from the bottom of the stack above, it dropsonto the top of the stack which accumulates below, keeping the slides inthe same order. When all the slides of the original stack have beenviewed, they may be removed and replaced with another stack.

BRIEF DESCRIPTION OF DRAWINGS This invention may be more fullyunderstood by reference to the accompanying drawings showing a preferredembodiment of my invention, but dimensions in some views may vary fromother views for clarity of illustration, and wherein:

FIG. 1 is a perspective view showing the slide changer with a stack ofslides applied to a well-known type of overhead projector;

FIG. 2 is a similar view with the stack of slides removed;

FIG. 3 is a fragmentary front elevation of the machine shown in FIGS. 1and 2 showing one arrangement for attaching the slide changer to theprojector, a portion only of the machine and tray being shown;

FIG. 4 is a side elevation on a larger scale of the apparatus as shownin FIG. 3 with the tray and motor housing in section;

FIG. 5 is a fragmentary plan view on a larger scale showing the relationof the two shafts or spindles and the slide sweep arm arrangement;

FIG. 6 is a schematic wiring diagram for the motor;

FIG. 7 is a plan view of a single slide;

FIG. 8 is also a plan view of a single slide with the exhibit crosswiseinstead of lengthwise as in FIG. 7;

FIG. 9 is a corner detail of a slide with a non-circular eye or grommet;

FIG. 10 is a transverse section through FIG. 9; and

FIG. 11 is a perspective view of a slide holder.

In the accompanying drawings 1 have, for purposes of illustration,disclosed one well-known type of overhead projector to which theinvention is adapted, and it should be understood that certainmodifications in hardware of the present invention may be necessary withprojectors of other makes which are not of exactly the same contour. Forthe purposes of describing this invention, they are essentially thesame.

The projector itself as here illustrated comprises a generally cubicallight box 2 having an enlarged frame portion 3 around its top. It has alight-transmitting or translucent top 4 mounted in the frame 3. There isa post 5 on what may be termed the rear side of the frame on which is anarm 6 supporting the projector 7 which is arranged to gather lightprojected upwardly through the light-transmitting top 4 and project ithorizontally through a projection lens 8. A knob 9 accessible at thefront of the machine serves to raise or lower the post 5 for focusingpurposes. The box has or may be provided with laterally extending baseflanges 10 along each side thereof and in the environment here shownthis base flange provides for the attachment of the automatic slidechanger of the present invention to the light box.

As most clearly shown in FIG. 3, there is a bracketlike housing elementdesignated generally as 11 having a bottom 12, a top 13, and an end wall14. The bottom plate 12 at the left of the housing element as shown inFIG. 3 projects beyond the vertical wall 14 and there is a lip 15 spacedabove this projecting portion of the base which carries a clamping screwarrangement 16 having a pad 17 at its lower end. The base flange 10 atthe right side of the projector box extends under the overhanging lip 15and by turning the thumb screw arrangement 16, the housing assembly 11can be clamped to the base flange of the projector unit.

A deep tray 20 is removably set on this bracket with its top edge levelwith or below the light box. It has a bottom 21 and side and end walls,the rear end wall 22 having a deep finger-slot for convenience inremoving a stack of slides after they have been exhibited, as will behereinafter more fully understood.

Contained within the bracket-like housing element 11 is a low speedreversible motor 25 that drives a composite spindle or shaft 26 havingan outer sleeve 27 and an inner vertically reciprocable shaft 28 with anarm 29 that extends radially through a vertical slot 30 in the sleeve.The terminal of the arm 29 rides on the surface of a circular orsemi-circular cam 31 having a high point 32 with a surface that slopestoward a low point 33 which is 90 removed from the high point.

The top portion 27a of the shaft 27 is non-circular in section or has alongitudinal key that extends down to an offset at 34 and the innershaft 28 operates a slidedropping mechanism at 35 which is similar tomecha nisms used on conventional record changing phonographs forsuccessively dropping the lowermost record in a stack onto a turntablewhile the ones above are supported from dropping, devices of this kindbeing well known in the art. When the shaft 26 with its sleeve 27 androd 28 are at one limit of rotation, the arm 29 is at the lowermostposition on the cam 31, but as the shaft rotates 90 this arm rides tothe highest point on the cam 31, tripping the release mechanism at 35 todrop a slide, as hereinafter described, while supporting the remainingones above.

In FIG. 1 a stack of these slides, to be hereinafter described indetail, but which are generally square, are shown on the upper portion27a of the shaft or spindle 27 in a position which they normally occupyover the tray 20 when the shaft is at one limit of its rotation and thearm 29 is at the lowest position on the cam 31. Each slide has anon-circular hole or keyway in one corner, so that when the shaftrotates clockwise from the position shown in FIG. 1 the stack of recordsis then centered over the light box.

The bracket-like housing 11 also supports a second vertical shaft 45which is parallel with the composite shaft 26 and which passes upthrough an enlarged opening at 46 in the bottom of the tray. This secondshaft has a sweep arm 47 pivoted to its upper end so that it normallyextends horizontally over the top of the light box. The vertical axis ofthe shaft 45 is so located on a diagonal line extending from the axis ofcomposite shaft 26 generally toward the nearest corner of the light boxso that the sweep arm can swing horizontally from a normal positionwhere its straight edge 47a, which I term its forward edge, is aboutparallel with and just clear of the rear edge of a slide which is inposition on top of the light box to be exhibited through an arc of atleast 90 and preferably a little more than 90 to a second position whereit is parallel, or slightly past being parallel with that side of thetray- 20 which is close against the side of the light box. The rear edgeof the sweep arm comprises a wedgelike segment 47b or trailing extensionof such shape and dimension as to extend well in toward and preferablynever entirely clear the edge of the glass top of the light box.

The outer sleeve 27 of the composite shaft 26 has a gear wheel 48 fixedthereon and this gear wheel meshes with a gear wheel 49 fixed on theshaft 45, or is otherwise arranged to be rotated when the shaft 26 isrotated through an arc of at least 90 or slightly more, perhaps but inthe opposite direction. This is indicated by the gear wheel 49 beingslightly less in diameter than gear 48, but where space does not permit,the gearing may be otherwise arranged. I

The slides are desirably made of slightly stiffer material than thosenow commonly used, or they may be the same, and each one is then mountedin a separate adapter. Usually each slide has a four-sided opaquecardboard frame from which three corners are cut away. The subject to beillustrated is reproduced on a transparent acetate" or similar film anda thin adhesive tape at the comers and along the sides. With the presentinvention the same structure may be followed, but instead of the openspace in the frame being concentric, the card of the present invention,in addition to being formed of a stiffer or less flexible material, ismade as shown in FIG. 7 where the frame 50 for a transparency that isvertical is square, but the area for receiving the transparent sheet islocated so that one side 51 is wider than the other three sides and thebottom strip is slightly wider than the top one. In FIG. 8 the frame 50afor a transparency that is viewed lengthwise has the opening elongatedhorizontally as viewed in this figure in contrast to the verticalelongated space within the frame 50 of FIG. 7. In each case the openingin the frame is desirably the same distance from the top of the frame.Each frame has a grommet or eyelet 52 in the upper right-hand corner asviewed in these figures, the grommet having a non-circular opening orkeyway therethrough so that the frames or slides will be received on theupper portion 27a of the post or shaft 27 as previously described. Aspreviously described they will not rotate relative to said portion butwill freely rotate on the lower portion 27 of this shaft. In FIGS. 9 and10 these eyelets or grommets 52 are shown in enlarged detail.

In place of forming the slides or cards with an eyelet in this manner,an adapter in the form of metal or plastic holder 55, such as that shownin FIG. 11 may be used. A cardboard frame with its transparency may beremovably received or held by one of the holders, there being one holderfor each card or slide in the series to be exhibited. The holder has anopening 56 through one corner so that it is non-rotatable but held onthe shaft extension 27a but slidable and rotatable on the sleeve shaft27 below the release 35. The term slide or slide unit as used herein isintended to mean either the transparency itself with the frame in whichit is mounted, or the mounted transparency and bolder, unless otherwisespecified.

Referring to FIG. 6, a remote control circuit for the reversing motor 25is schematically indicated. The power for operating the motor may bederived from the same source of power to which the lights in the lightbox are connected, as indicated by the transformer 60. One slide 61, ofthe transformer secondary is connected with the motor and the other sideis connected through an extension cord 62 and a push-button 63 with atoggle or snap-over type of switch 64, one contact 65 of which leads tothe motor to drive it in one direction, and the other contact 66 ofwhich connects to the motor to drive it in the opposite direction. Theswitch may be operated by some well-known device built into the motoror, as here indicated, by being in the path of movement of an arm 67extending radially from the shaft 27.

The operation is as follows: The stack of slides on the portion 270 ofthe shaft 27 is normally over the tray at the side of the light box.Starting with the first slide, the exhibitor presses button 63,energizing motor to rotate the composite shaft 26-27a which rotates thestack of records 90 to a position over the light box at the same timemoving the sweep arm 47 over the top of the light box in the oppositedirection until its edge 47a is above the tray 20. As this takes place,arm 29 rides up the cam 21 so that when the stack of slides reaches itsfurthese limit of travel with the stack properly centered above theglass top 4 of the light box, the lowermost slide will be released bythe mechanism 35 and dropped into position over said glass. However oneedge will fall on the wedge-like segment 47b of the sweep arm 47. As theslide is dropped in the manner described, and with the circuit stillenergized, switch 64 snaps to the reverse position and the shaft 26- 27swings back to itd normal position under the tray while the sweep armslides back under the slide to its normal position, allowing the slideto drop down where it is then flat and in focus to be exhibited. At thistime the operator releases the push-button switch, and reversing switch64 at this time will then be reset for the next cycle. When he wishes toexhibit the next slide, the operator again pushes the button, but onthis and succeeding cycles the straight edge 47a of the sweep arm willhit the back edge of the slide that he has just shown and push it,counter to the direction in which the stack is rotating through an arcwhere that slide will drop off into the tray, of course sliding down thesleeve shaft 27. Each slide in turn is exhibited in this fashion andwhen the stack is completed, the operator lifts all of the slides as agroup up and off the composite shaft 26 with its upper portion 270. Allof the records will then be in the order in which they were exhibited.The finger slot 22 in the tray facilitates this removal of the stack ofexhibited slides.

If at any time the entire tray is to be removed, it is simply raised upto clear the top of portion 27a and because of the sweep arm beingpivoted, and with an adequate opening in the bottom of the tray, thetray will raise the sweep arm to a vertical position and clear it.

I claim:

1. For use with an overhead type of projector, a remote controlledslide-changing attachment comprising:

a. a support structure arranged to be mounted alongside the light box ofan overhead projector wherein the light bod has a light-transmittingcover glass and a frame at the top around the cover glass,

b. a reversible motor-driven spindle on the support positioned toproject vertically up at one corner of the light box, the spindle havingan upper end portion projecting above the level of the top of the boxarranged to pass through the corner portions of and support a stack ofslide units with visual subjectmatter to be exhibited with the lowermostslide unit above the level of the top of the light box and with theslide units being non-rotatable on the spindle, the lower portion of thespindle below the top of the light box being so arranged that thespindle rotates freely relatively to the slide units,

c. a reversible motor for rotating the spindle through an are between aposition where the stack of slide units on the upper portion of thespindle is between a first position clear of the light box and a secondposition where said stack is squarely over the top of the light box,

d. means operable with the rotation of the spindle to the secondposition for releasing the lowermost slide unit in the stack to movedown the spindle onto the lower portion of the spindle with the slideunit coming to rest on the top of the light box where it is positionedfor visual subject-matter on the slide to be projected, and

e. means operated by the motor for removing a previously exhibited slideunit from off the top of the light box to a position at one side of thelight box where it is free to move down the lower portion of the spindleand remain stationary while other slide units on the spindle are beingsimilarly cycled.

2. The invention defined in claim 1 in which there is a tray at one sideof the light box through a corner of which said spindle extends, thetray being in a position to receive the slide units when they are movedoff the top of the light box and are free to move down the spindlewhereby they are collected in the tray.

3. The invention defined in claim 1 in which said lastnamed means movesthe slide from off the top of the light box simultaneously with themovement of the stack toward said second position.

4. The invention defined in claim 3 in which said means for moving eachslide unit in turn after it has been exhibited from off the top of thelight box comprises a second spindle parallel with the first with ahorizontally extending sweep arm fixed thereto for rotation therewithand gearing for reversing the direction of rotation of the secondspindle relatively to the first between a starting position and a.position where it will have removed the slide unit off the top of thelight box.

5. Apparatus as defined in claim 4 in which said sweep arm issegment-shaped with a leading edge arranged to contact an edge of theslide unit and with a trailing edge, the sweep arm being so positionedon its spindle that when it has reached a position where the slide unitwhich has been exhibited has moved off the light box the trailing edgeof the sweep arm will be in a position where the next slide moving downinto place will overlap said trailing edge to enable the sweep arm toreturn to its starting position by moving under the slide which has thusmoved down.

6. Apparatus as defined in claim 1 wherein said support is removablyclamped to the light box.

7. Apparatus as defined in claim 1 wherein the upper portion of thespindle is non-circular in section and each slide unit has aspindle-receiving opening in one corner arranged to slidably butnon-rotatably engage the spindle whereby the stack of slide units willrotate with the shaft and will slide down said spindle as the lowermostone drops away to be exhibited.

8. Apparatus as defined in claim 7 wherein each slide unit comprises atransparency on which is the visual subject-matter to be projected, aframe around the transparency and a holder in which the frame with itstransparency is removably received and supported, the holder having thehole therethrough into which the upper portion of the spindle isnon-rotatably fitted.

9. Apparatus as defined in claim 1 wherein there is an electric circuitincluding a push button switch for initiating the operation of the motorto move the stack from the first to the second position and amotoractuated switch for reversing the motor after a slide unit has beenreleased from the bottom of the stack onto the light box and return thestack to its first position with the stack clear of the space above thelight box.

1. For use with an overhead type of projector, a remote controlledslide-changing attachment comprising: a. a support structure arranged tobe mounted alongside the light box of an overhead projector wherein thelight bod has a light-transmitting cover glass and a frame at the toparound the cover glass, b. a reversible motor-driven spindle on thesupport positioned to project vertically up at one corner of the lightbox, the spindle having an upper end portion projecting above the levelof the top of the box arranged to pass through the corner portions ofand support a stack of slide units with visual subject-matter to beexhibited with the lowermost slide unit above the level of the top ofthe light box and with the slide units being non-rotatable on thespindle, the lower portion of the spindle below the top of the light boxbeing so arranged that the spindle rotates freEly relatively to theslide units, c. a reversible motor for rotating the spindle through anarc between a position where the stack of slide units on the upperportion of the spindle is between a first position clear of the lightbox and a second position where said stack is squarely over the top ofthe light box, d. means operable with the rotation of the spindle to thesecond position for releasing the lowermost slide unit in the stack tomove down the spindle onto the lower portion of the spindle with theslide unit coming to rest on the top of the light box where it ispositioned for visual subject-matter on the slide to be projected, ande. means operated by the motor for removing a previously exhibited slideunit from off the top of the light box to a position at one side of thelight box where it is free to move down the lower portion of the spindleand remain stationary while other slide units on the spindle are beingsimilarly cycled.
 2. The invention defined in claim 1 in which there isa tray at one side of the light box through a corner of which saidspindle extends, the tray being in a position to receive the slide unitswhen they are moved off the top of the light box and are free to movedown the spindle whereby they are collected in the tray.
 3. Theinvention defined in claim 1 in which said last-named means moves theslide from off the top of the light box simultaneously with the movementof the stack toward said second position.
 4. The invention defined inclaim 3 in which said means for moving each slide unit in turn after ithas been exhibited from off the top of the light box comprises a secondspindle parallel with the first with a horizontally extending sweep armfixed thereto for rotation therewith and gearing for reversing thedirection of rotation of the second spindle relatively to the firstbetween a starting position and a position where it will have removedthe slide unit off the top of the light box.
 5. Apparatus as defined inclaim 4 in which said sweep arm is segment-shaped with a leading edgearranged to contact an edge of the slide unit and with a trailing edge,the sweep arm being so positioned on its spindle that when it hasreached a position where the slide unit which has been exhibited hasmoved off the light box the trailing edge of the sweep arm will be in aposition where the next slide moving down into place will overlap saidtrailing edge to enable the sweep arm to return to its starting positionby moving under the slide which has thus moved down.
 6. Apparatus asdefined in claim 1 wherein said support is removably clamped to thelight box.
 7. Apparatus as defined in claim 1 wherein the upper portionof the spindle is non-circular in section and each slide unit has aspindle-receiving opening in one corner arranged to slidably butnon-rotatably engage the spindle whereby the stack of slide units willrotate with the shaft and will slide down said spindle as the lowermostone drops away to be exhibited.
 8. Apparatus as defined in claim 7wherein each slide unit comprises a transparency on which is the visualsubject-matter to be projected, a frame around the transparency and aholder in which the frame with its transparency is removably receivedand supported, the holder having the hole therethrough into which theupper portion of the spindle is non-rotatably fitted.
 9. Apparatus asdefined in claim 1 wherein there is an electric circuit including a pushbutton switch for initiating the operation of the motor to move thestack from the first to the second position and a motor-actuated switchfor reversing the motor after a slide unit has been released from thebottom of the stack onto the light box and return the stack to its firstposition with the stack clear of the space above the light box.